Here's a few others:
- Evard's Rodwalker. Casting Black Tentacles wherever it goes, this mech can be a true terror for enemy mechs. Sidenote: it probably requires some houseruling. Basically alter combine spell so that casting 4 Evard's Black Tentacles at a time makes tentacles big enough to actually grapple a mech.
- Black Legionaire. A creation of the Shadow Congress, this mech surveys old battlefields and casts Animate Dead. If that's not to your liking, then this is a variant belonging to a defector now in service of Sharlorn the Necropolis.
- Legion. (Ok, so the name is too similar to the last. Cut me some slack!) Mass Enlarge Person. So you can't field a lot of mechs in a hurry? Why not bring your infantry up to mech size? If only there were an Enlarge Monster spell...
- Dispel Magic. A specialty mech used to hunt down defectors, rogue necromancers, and Shadow Congress agents, this mech excels at removing enemies from the fight entirely. With the help of constructors, other variants exist, making use of Tick Tock Knock, Gearghoul Touch, Bestow Malfunction, or Inflict Damage.
- Web. Used mainly against infantry, and a drow variant of the Rodwalker.
- Grease. The ideal way to shut down unskilled mech pilots. Works particularly well with regular Rodwalkers, as the oilslick is quite flammable.
Of all of these, I particularly like the Dispel Magic (and variants) and the Web one. Actually, I really like web. Perhaps it's only suited to anti-infantry, but damn if it isn't cool.
I am Omnirahk, half-Rahkshi ("Omni") of the WotC forums. I consider "Psionics in DragonMech" (see my website) my greatest contribution to anything d20 so far. At least, it's my most successful topic.